diff --git a/compiler/nadd.pas b/compiler/nadd.pas
index 9b4b1db124..5731e1241b 100644
--- a/compiler/nadd.pas
+++ b/compiler/nadd.pas
@@ -2511,7 +2511,6 @@ implementation
 {$endif cpuneedsmulhelper}
       begin
          result:=nil;
-{$ifndef jvm}
          { Can we optimize multiple string additions into a single call?
            This need to be done on a complete tree to detect the multiple
            add nodes and is therefor done before the subtrees are processed }
@@ -2520,7 +2519,6 @@ implementation
              result := genmultistringadd(self);
              exit;
            end;
-{$endif jvm}
          { first do the two subtrees }
          firstpass(left);
          firstpass(right);
diff --git a/rtl/java/compproc.inc b/rtl/java/compproc.inc
index 2d524f5e56..a4a1a5fcd4 100644
--- a/rtl/java/compproc.inc
+++ b/rtl/java/compproc.inc
@@ -308,7 +308,7 @@ Function fpc_AnsiStr_To_UnicodeStr (Const S2 : AnsiString): UnicodeString; compi
 Function fpc_UnicodeStr_To_WideStr (const S2 : UnicodeString): WideString; compilerproc;
 Function fpc_WideStr_To_UnicodeStr (Const S2 : WideString): UnicodeString; compilerproc;
 Function fpc_UnicodeStr_Concat (const S1,S2 : UnicodeString) : UnicodeString; compilerproc;
-function fpc_UnicodeStr_Concat_multi (const sarr:array of Unicodestring): unicodestring; compilerproc;
+procedure fpc_UnicodeStr_Concat_multi (var DestS:Unicodestring;const sarr:array of Unicodestring); compilerproc;
 Function fpc_Char_To_UnicodeStr(const c : AnsiChar): UnicodeString; compilerproc;
 Function fpc_CharArray_To_UnicodeStr(const arr: array of AnsiChar; zerobased: boolean = true): UnicodeString; compilerproc;
 
diff --git a/rtl/java/ustrings.inc b/rtl/java/ustrings.inc
index 6bef59066a..ad333f6d79 100644
--- a/rtl/java/ustrings.inc
+++ b/rtl/java/ustrings.inc
@@ -141,7 +141,7 @@ begin
 end;
 
 
-function fpc_UnicodeStr_Concat_multi (const sarr:array of Unicodestring): unicodestring; compilerproc;
+procedure fpc_UnicodeStr_Concat_multi (var DestS:Unicodestring;const sarr:array of Unicodestring); compilerproc;
 Var
   i  : Longint;
   Size,NewSize : SizeInt;
@@ -158,7 +158,7 @@ begin
       if length(sarr[i])>0 then
         sb.append(sarr[i]);
     end;
-  result:=sb.toString;
+  DestS:=sb.toString;
 end;